M30 progress:
Objective 1 - Up to 95 % bio-sourced fast curing thermoset resin formulations as matrix component for advanced lightweight composites applications
Bio-based Epoxy resin development
In this reporting period, the recipes have been further characterised to evaluate their processability into composite parts.
One recipe has shown a higher potential for processing showing a longer open time (time during which the viscosity is low enough for proper processing).
It has been further optimised to improve curing time and fire resistance.
Two cure initiators have been tested, one of them giving promising results with a maximum Tg of 180°C, which should be further investigated after the project.
A variety of bio-based fire retardants have also been evaluated, two of which are meeting the requirements.
Bio-based UPR resin development
More than 47 recipes have been tested using ten bio-based monomers, 22 of which have been shortlisted as showing a adequate viscosity profiles. The most promising candidates have been processed into neat resin coupons and mechanically tested.
Three recipes have given good mechanical results either comparable or outperforming the petrol-based reference of the project.
It has not been possible to fully substitute styrene in any of the best candidates and a compromise must be done to select the most promising one.
Objective 2 - Development of sustainable (bio sourced, recycled...) continuous fibres for surface transport and aerospace industries.
Recycled glass fibre development
In the M18-M30 period LIPEX have worked with the recycled glass supplier to improve the purity of the glass reclaimed from wind turbine blades. They have received a larger quantity of recycled glass and transformed it into roughly 80kg of new fibre on a pilot line.
The produced glass fibre will now be processed into a fabric to facilitate the processing activities in WP3.
A pilot plant has been designed and discussed with potential industrial customers in France and in the UK.
Cellulose based fibre
In the M18-M30 period, work has been done to improve the interfacial properties of cellulose fibres by blending cellulose with lignin. A variety of blends have been produced and spun. Mechanical tests have been performed on both single fibres and composite coupons.
Lignin-based carbon fibre
In the M18-M30 period, CTB have shortlisted two components for lignin-based precursor yarn production. Lignin with a high content of β-O-4 has been combined with PA5.13 at various contents. Different spinneret configurations have been tested: continuous, core-sheath and islands-in-the-sea, the latter being abandoned.
NTUA have continued efforts to stabilize multifilament fibres that involved increasing filament counts and applying the lowest possible heating rates. Double bundles of fibers withstood the stabilization process under specific conditions. Chemical crosslinking solutions, including Formaldehyde, Hydrochloric acid, Phosphoric acid, and Boric acid, were also investigated. Thermal stabilization involved two thermal cycles, but only formaldehyde-treated PA5.13 fibers endured the process.
Recycled carbon fibre
In the M19-M30 period, modifications of the spinning line have been completed. ITM have observed a varying level of quality in the rCF received from the supplier affecting the quality of the staple yarn. A batch of rCF giving satisfaction has been secured with the supplier and production of a staple yarn meeting the project requirements has started.
Objective 3 - One-shot production processes for sustainable structural composites
In the M19-M30 period, processing of some the materials developed in the project has started.
The first samples of recycled carbon fibre yarn and regenerated cellulose yarn produced in WP2 have been processed by Tailored Fibre Placement (TFP) to produce reinforcements, which were then impregnated by resin infusion, validating the processability of the materials.
A fully bio-based epoxy resin developed by Orineo with improved mechanical properties has been processed in a composite panel with commercial glass fibre.
A fully-bio-based epoxy resin developed by UCA has been used for processing trials. It has not been possible to reach the full impregnation of a glass reinforcement due to a short processing window. The resin viscosity increased too fast and process adjustments have been discussed between WP1 and WP3 to find a solution, causing delays in the availability of the composite panels due for characterization.
Regarding the bio-based UPR resin, composite panels have been produced by infusion and panels have been sent for mechanical testing as planned.
The processing of the UPR resin into an SMC (Sheet Material Compound) semi-product has not been straightforward and a good collaboration between Megara Resins, Compositec and an SMC supplier has led to successful trials.
Objective 4 - Optimised and new recycling technologies, environmental and cost analysis
Solvolysis process:
Orineo have identified ethyl lactate as a biodegradable solvent for the Oribond resin. The solvent will now be tested on composite panels.
UCA have tested various processes and products for the solvolysis of the bio-based epoxy resin yielding to a 69%w recovery of the product. The recycled product could be mixed with fresh epoxy to produce a new resin, but mechanical properties have significantly dropped.
Innovative pyrolysis process:
The design of a pyrolysis line using the gases produced from NTUA’s carbonisation lines has been finalised. It has been found that a 50x50x50cm3 volume was not achievable without additional heating. The volume has been reduced to 35x35x35cm3.
The carbonisation line modification is ongoing and is due for delivery in M31. Pyrolysis tests have been made in a conventional oven to learn about the process parameters.
LCA/LCC analysis:
LCA tools have been used to identify hotspots and support ingredient selection in resin development activities. The results have also been used to demonstrate the positive impact of the bio-based/recycled material approach on the environmental impact of composite structures.
